You probably don't think about body odour all that much, until you're at the gym or on a crowded bus. You roll on your roll-on each morning and that's usually that. From time to time, you may detect a scent emanating near you and wonder, "Could that be me?" You do a quick, discreet sniff test of your armpits and look around to see if anyone noticed or whether the scent could belong to someone else. From where do these offending smells sprout? Why does the human body sometimes emit such a foul stench?

To understand why body odour happens, it helps to know a little bit about sweat. You have about 2 to 4 million sweat glands all over your body, but these millions of glands come in 3 main types - eccrine, apocrine, and apoeccrine sweat glands.

The sweat that cools:Eccrine sweat glands span your body's length, from your head to your feet. From your eccrine glands come the sweat of nervousness, the sweat of exertion, and the sweat in response to heat. Eccrine glands serve a definite function: they help our body adjust its temperature. The sweat from these glands is slightly salty but odourless. You may be wondering about feet, then, and why they smell. The feet can smell because of bacteria that thrive in dark, tight places (like shoes and socks).

The sweat that stinks:Apocrine sweat glands, on the other hand, don't serve a direct purpose. And while they can only be found in a few distinct places - a few of the more intimate or hidden parts of our bodies - the sweat radiating from these spots tends to be the smelliest. Yes, we're talking about the underarms, but we're also talking about the areas around the genitals, nipples, and belly button area. Because of the location of these glands, the theory is that they once served some sexual function. When moisture originates in these spots, it interacts with bacteria on the skin, causing each person's distinct body aroma.

The combo sweat:Apoeccrine sweat glands are, as you can tell, a combination of the other two types of sweat glands. These are found in the underarms and bum areas and they are developed from eccrine glands during puberty. Scientists are unclear on the role of these glands.

Luckily, it's pretty simple to deal with body odour:

keep yourself clean and shower after especially exerting activities

use deodorant

wear natural fibre clothing that lets your skin breathe

stay active so your body flushes out potential bacteria

cut back on any foods, like garlic, that seem to cause particularly foul body odour

Everyone sweats when they're hot or nervous or moving around a lot. Excessive sweating (hyperhidrosis) is less common and may be caused by genetics, certain foods or medications, hormonal imbalances, low blood sugar, certain diseases and conditions, or by an unknown source. You should see a doctor if you notice a new or strong scent to your usual body odour or if you're sweating more than usual.